(a) Field of the Invention
The present invention relates to a thin film transistor array panel and a method of manufacturing the same.
(b) Description of the Related Art
In general, a flat panel display such as a liquid crystal display (“LCD”), an organic light emitting diode (“OLED”) display, and an electrophoretic display includes a plurality of pairs of field generating electrodes and electro-optical active layers interposed therebetween. The LCD includes a liquid crystal layer as the electro-optical active layer, and the OLED display includes an organic light emitting layer as the electro-optical active layer.
One field generating electrode forming one pair of the field generating electrodes is generally connected to a switching element to receive an electrical signal, and an electro-optical active layer converts the electrical signal to an optical signal, thereby displaying an image.
In the flat panel display, a thin film transistor (“TFT”), which is a three terminal element, is used as the switching element, and a gate line that transfers a scanning signal for controlling the TFT and a data line that transfers a signal to be applied to a pixel electrode are provided in the flat panel display.
Research into organic thin film transistors (“OTFTs”) including an organic semiconductor instead of an inorganic semiconductor, such as silicon (Si) among the TFTs, has been actively conducted.
Since the OTFT can be manufactured in a fiber or film form in view of characteristics of an organic material, it has been in the spotlight as a core element of a flexible display device.
Furthermore, because the OTFT can be manufactured with a solution process at a low temperature, the OTFT can be easily applied even to a large flat display being only limited by a deposition process thereof.
An inkjet printing method among the solution processes is a method of dropping an organic solution in a predetermined area defined by an insulating bank and which can easily form an organic thin film such as an organic semiconductor or an insulating film.
However, an organic thin film formed by the inkjet printing method has a non-uniform thickness. In particular, a part of the organic semiconductor which comes in close contact with the insulating bank is formed thick and a part of the organic semiconductor far apart from the insulating bank is formed thin, due to surface characteristics of an organic semiconductor and an insulating bank surrounding the semiconductor. In this case, a non-uniform thickness in a portion of the organic semiconductor in which a channel is formed may influence characteristics of the TFT.
Furthermore, the OTFT has a different structure and manufacturing method compared to existing TFTs. For example, as the number of masks required for manufacturing the OTFT increases, the cost of manufacturing the OTFT increases remarkably.